The present invention concerns a rocket propulsion unit with an outer casing and an inner casing whereby the inner casing, also called the liner, is arranged with a space between the outer casing and inner casing. The inner casing forms a combustion chamber and a contour adapted to the expulsion of propellants out of the combustion chamber with a constriction to form a combustion chamber neck.
Rocket propulsion units, which have a structure on the basis of an outer casing and an inner casing have been known for a long time as being the state of the art. Hereto, reference is made to DE 199 01 422 as an example. With such rocket propulsion units, the inner casing, which can contain a cooling structure, and the outer casing are connected firmly with each other. The outer casing can be, for example, galvanized to the inner casing.
U.S. Pat. No. 5,899,060, in contrast, shows a rocket propulsion unit in which the inner casing and the outer casing are arranged with a spacing of a constant distance between each other and have the same contour, whereby in the operating condition of the rocket propulsion unit, the inner casing is pressed to the outer casing, so that the outer casing supports the inner casing.
A disadvantage with the aforementioned state of the art technology is, however, that the inner casing and outer casing must use a costly adaptation to each other and thus an optimization of the entire structure must constantly take place with possible required changes in the combustion chamber region. Expensive connections between the inner casing and outer casing as well as galvanic connections or welded joints are also necessary. If a part of the structure is damaged by an operation, then as a rule the entire propulsion unit cannot be reused.
An object of the present invention is to provide a rocket propulsion unit, which requires the simplest production possible, especially, a low expense for optimization of the individual components. This object is achieved according to certain preferred embodiments of the invention by providing a rocket propulsion unit with an outer casing and an inner casing, whereby the inner casing is arranged with a space between the outer casing and inner casing, and the inner casing forms a combustion chamber, and has a contour adapted for expulsion of propellants from the combustion chamber with a constriction to form a combustion chamber neck, wherein the outer casing has a contour deviating from the contour of the inner casing.
According to the invention, the rocket propulsion unit has an outer casing and an inner casing, whereby the inner casing is arranged with a space between the outer casing and inner casing. The inner casing forms a combustion chamber and has a contour adapted to the expulsion of propulsion liquids from the combustion chamber with a constriction forming a combustion neck. In accordance with this invention, it is now provided that the outer casing is not adapted to this contour of the inner casing, but has a contour deviating from the contour of the inner casing. The local distances between the inner casing and outer casing are, therefore, as a rule, not constant but vary according to the different contours of the inner casing and outer casing. This is, however, not a problem, since it is not provided for the inner casing to be close to the outer casing (for example, by pressing on in the operating state). The inner casing merely has to have a sufficient strength in order to be able to match the stresses arising in the combustion chamber during the operation. Thus the results are a broad based functional separation of inner stress-bearing structure and outer stress-bearing structure of the rocket propulsion unit.
In this way, the outer casing can be configured independently from the possible optimization-required contour of the inner casing. For example, a standard structure can be established for the outer casing that can be maintained largely constant during the entire development phase of a propulsion unit or even for an entire propulsion family unit. Thus the development of production of rocket propulsion units is basically simplified and configured more cost efficiently. The inner casing and outer casing can also be optimized largely without reciprocal affects with regard to their structure, material, durability and rigidity or elasticity.
A further cost optimization can be achieved by designing the inner casing to be interchangeable according to certain preferred embodiments of the invention. The inner casing is exposed to high operating temperatures, which restricts the economic life of the inner casing. With previous rocket propulsion systems, the economic life of the entire propulsion unit is thus automatically limited. If, however, the inner casing is designed interchangeably, which in particular can be realized through corresponding detachable connections between the inner casing and outer casing, then the remaining structure of the propulsion unit can be reused, which considerably reduces the cost and also the time needed for recovery of the propulsion unit.
Specifically, it can be provided according to certain preferred embodiments of the invention that the inner casing and the outer casing are joined with one another only in the regions of the ends of the inner casing. Therewith, the greatest possible freedom in configuring the inner casing and the outer casing can be achieved and, on the other hand, the necessary connections between the inner and outer casing are reduced to a minimum.
To compensate for thermal expansion between inner casing and outer casing, it can be provided according to certain preferred embodiments of the invention that the inner casing is firmly connected in the region of a first end (in the event of an interchangeable inner casing immobile, but detachable) with the outer casing, and is mounted longitudinally movable in a region of a second end in a bearing.
As already mentioned, the invention allows selection of a standard structure for the outer casing which is independent from the special contouring of the combustion chamber. In this case, the standard structure can largely be selected as a geometrically very simple form. Thus it can be provided specifically that the outer casing has a basically tube-like contour according to certain preferred embodiments of the invention. Thus, the outer casing forms a housing, enclosing the inner casing, in which the inner casing is arranged. xe2x80x9cBasically tube-likexe2x80x9d means that in certain sub-regions, especially where inner casing and outer casing are joined together, the contour of the outer casing can be approximated to the contour of the inner casing. Thus, especially the outer casing can spread out in the area of the open end of the combustion chamber. In this area, downstream from the combustion chamber neck, the combustion chamber as well as the inner casing widen. Thus, a connection of outer casing and inner casing can be facilitated in this region.
In order to withstand the high temperatures in the combustion chamber, the inner casing can contain a cooling system according to certain preferred embodiments of the invention. But it can also be provided that the inner casing is made of a correspondingly high temperature-resistant material, especially of ceramic.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.